Ecotypic differentiation in populations of Ruppia maritima L. germinated from seeds and cultured under algae-free laboratory conditions

Abstract

Ruppia maritima L. from the west coast of Florida and North Carolina was grown from seeds under common garden conditions and showed the same pattern in growth and photosynthetic rates when exposed to different temperatures (14, 22, 30°C) or photoperiods (6, 12, 18 h L) but showed different responses to the salinities tested (10, 20, 30ℵ). Photosynthetic responses were significantly higher for the northern population due to significantly elevated levels of Chl a in the North Carolina population. It is proposed that ecotypic differentiation with relation to levels of Chl a and photosynthetic responses to salinity have occured between two R. maritima populations. This differentiation may be due to the different salinity regimes from which the seeds were collected. In contrast, no differentiation with relation to temperature or photoperiod is evident, perhaps reflecting the similar conditions for these two parameters during the growing season of R. maritima in these two habitats.